Viscosity measurements of Zr 55Cu 30Al 10Ni 5 and Pd 40Cu 30Ni 10Pi 20 supercooled liquid alloys by using a penetration viscometer

Abstract

Viscosity of Zr 55Cu 30Al 10Ni 5 and Pd 40Cu 30Ni 10Pa 20 supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a cylindrical probe under high speed heating conditions at heating rates between 20 and 400°C/ min in the temperature range from the glass transition temperatures (T g) up to above the crystallization temperatures. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200°C/min and above. Their viscosity could be well represented by the Arrhenius relation. The activation energies for viscous flow for Zr 55Cu 30Al 10Ni 5 and Pd 40Cu 30Ni 10P 20 supercooled liquid alloys were about 350 and 250kJ/mol, respectively. The viscosity was also fitted by a Vogel-Fulcher-Tammann (VFT) relationship over the entire temperature range. © 2005 The Japan Institute of Metals.